Aug 5 Knocks in the woods.

I'm trying to understand their wood knocks, and it seems I've found a volunteer to help me. For the last couple of days, I've been spending some time in the back acreage, knocking with them after my Grandma claimed to hear knocks at around 3 am. It took maybe 25 min to get a response, but this is the outcome. I entered the woods and gave one knock. I didn't hear a response so I tried a combination knock 2 1 2 1 1. And nothing. I tried all kinds of different combinations for about 25 min before I just sat down and waited to see if I could hear anything. I was about to head home until I heard A reply 2 2 2. Then the fun began.